[S390] cio: move device unregistration to dedicated work queue

Use dedicated slow path work queue when unregistering a device due to
a user action. This ensures serialialization of other register/
unregister requests.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 25 insertions, 31 deletions

diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index 28221030b886..38a79ecfc743 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -296,36 +296,33 @@ static void ccw_device_unregister(struct ccw_device *cdev)
                 device_del(&cdev->dev);
 }
 
-static void ccw_device_remove_orphan_cb(struct device *dev)
+static void ccw_device_remove_orphan_cb(struct work_struct *work)
 {
-        struct ccw_device *cdev = to_ccwdev(dev);
+        struct ccw_device_private *priv;
+        struct ccw_device *cdev;
 
+        priv = container_of(work, struct ccw_device_private, kick_work);
+        cdev = priv->cdev;
         ccw_device_unregister(cdev);
         put_device(&cdev->dev);
+        /* Release cdev reference for workqueue processing. */
+        put_device(&cdev->dev);
 }
 
-static void ccw_device_remove_sch_cb(struct device *dev)
-{
-        struct subchannel *sch;
-
-        sch = to_subchannel(dev);
-        css_sch_device_unregister(sch);
-        /* Reset intparm to zeroes. */
-        sch->schib.pmcw.intparm = 0;
-        cio_modify(sch);
-        put_device(&sch->dev);
-}
+static void ccw_device_call_sch_unregister(struct work_struct *work);
 
 static void
 ccw_device_remove_disconnected(struct ccw_device *cdev)
 {
         unsigned long flags;
-        int rc;
 
         /*
          * Forced offline in disconnected state means
          * 'throw away device'.
          */
+        /* Get cdev reference for workqueue processing. */
+        if (!get_device(&cdev->dev))
+                return;
         if (ccw_device_is_orphan(cdev)) {
                 /*
                  * Deregister ccw device.
@@ -335,23 +332,13 @@ ccw_device_remove_disconnected(struct ccw_device *cdev)
                 spin_lock_irqsave(cdev->ccwlock, flags);
                 cdev->private->state = DEV_STATE_NOT_OPER;
                 spin_unlock_irqrestore(cdev->ccwlock, flags);
-                rc = device_schedule_callback(&cdev->dev,
-                                              ccw_device_remove_orphan_cb);
-                if (rc)
-                        CIO_MSG_EVENT(0, "Couldn't unregister orphan "
-                                      "0.%x.%04x\n",
-                                      cdev->private->dev_id.ssid,
-                                      cdev->private->dev_id.devno);
-                return;
-        }
-        /* Deregister subchannel, which will kill the ccw device. */
-        rc = device_schedule_callback(cdev->dev.parent,
-                                      ccw_device_remove_sch_cb);
-        if (rc)
-                CIO_MSG_EVENT(0, "Couldn't unregister disconnected device "
-                              "0.%x.%04x\n",
-                              cdev->private->dev_id.ssid,
-                              cdev->private->dev_id.devno);
+                PREPARE_WORK(&cdev->private->kick_work,
+                                ccw_device_remove_orphan_cb);
+        } else
+                /* Deregister subchannel, which will kill the ccw device. */
+                PREPARE_WORK(&cdev->private->kick_work,
+                                ccw_device_call_sch_unregister);
+        queue_work(slow_path_wq, &cdev->private->kick_work);
 }
 
 /**
@@ -970,12 +957,17 @@ static void ccw_device_call_sch_unregister(struct work_struct *work)
 
         priv = container_of(work, struct ccw_device_private, kick_work);
         cdev = priv->cdev;
+        /* Get subchannel reference for local processing. */
+        if (!get_device(cdev->dev.parent))
+                return;
         sch = to_subchannel(cdev->dev.parent);
         css_sch_device_unregister(sch);
         /* Reset intparm to zeroes. */
         sch->schib.pmcw.intparm = 0;
         cio_modify(sch);
+        /* Release cdev reference for workqueue processing.*/
         put_device(&cdev->dev);
+        /* Release subchannel reference for local processing. */
         put_device(&sch->dev);
 }
 
@@ -1001,6 +993,8 @@ io_subchannel_recog_done(struct ccw_device *cdev)
                 PREPARE_WORK(&cdev->private->kick_work,
                              ccw_device_call_sch_unregister);
                 queue_work(slow_path_wq, &cdev->private->kick_work);
+                /* Release subchannel reference for asynchronous recognition. */
+                put_device(&sch->dev);
                 if (atomic_dec_and_test(&ccw_device_init_count))
                         wake_up(&ccw_device_init_wq);
                 break;